Sputtering target and method for manufacturing the same

Abstract

The present invention relates to a sputtering target capable of utilizing a warped cylindrical substrate as a constituent material, and a method for manufacturing the same. The method provides a novel sputtering target manufacturing method capable of eliminating warping of the cylindrical substrate even when the cylindrical target material is relatively long in the axial direction or even when heated during filling with a bonding material. The present invention provides a sputtering target manufacturing method characterized by measuring the warpage of the cylindrical substrate, performing processing to warp the cylindrical substrate in a direction opposite to the warped direction, arranging a plurality of cylindrical targets spaced apart in the axial direction outside the processed cylindrical substrate, and bonding the cylindrical substrate and the cylindrical targets using a bonding material.

Description

Technical Field

[0001] The present invention relates to a sputtering target including a cylindrical substrate and a plurality of cylindrical target materials and a method for producing the same, and in particular to a method for producing a sputtering target capable of using a cylindrical substrate that is warped due to bending deformation as a material. Background Art

[0002] In the manufacture of organic EL, liquid crystal displays, touch panels, and other display devices, magnetron sputtering using a flat-plate sputtering target in which a target material is bonded to a flat substrate is the mainstream method for forming transparent conductive thin films made of ITO or the like.

[0003] In recent years, rotary sputtering has become practical, in which a cylindrical sputtering target, with a target material bonded to the outer circumference of a cylindrical substrate, is rotated about its axis to perform sputtering. Compared to flat-plate sputtering targets, this rotary sputtering method achieves significantly higher utilization efficiency, resulting in higher productivity.

[0004] As glass substrates used in flat panel displays and solar cells grow in size, thin film formation on these larger substrates requires long, cylindrical sputtering targets exceeding 2 meters in length. However, manufacturing cylindrical targets exceeding 2 meters in length is difficult, so multiple cylindrical targets (also called "split targets") are arranged along the axial direction outside the long cylindrical substrate.

[0005] For example, Patent Documents 1 and 2 disclose that a sputtering target is manufactured by preparing a plurality of target materials obtained by dividing a target material into a plurality of target materials along the axial direction, arranging the plurality of target materials along the axial direction on the outer circumference of a cylindrical substrate, and bonding them with a bonding material.

[0006] As cylindrical sputtering targets become longer, as described above, the influence of the cylindrical substrate on warpage becomes significant. Cylindrical substrates exceeding 2 meters in length are particularly prone to significant warping, with the magnitude of this warping also being significant. Extensive warping of the cylindrical substrate can lead to uneven thickness of the bonding material, resulting in insufficient cooling in thinner areas of the bonding material, which can cause cracking during sputtering.

[0007] In recent years, sputtering equipment for forming films on larger 10th generation glass substrates has begun to be used, with the total length of the target exceeding 3 meters. When the total length of the target exceeds 3 meters, the problem of warping as described above becomes more pronounced.

[0008] Therefore, Patent Document 2 focuses on the eccentricity between the substrate and the target material and proposes the following method to suppress the eccentricity: before manufacturing the cylindrical target, the warping of the cylindrical substrate is confirmed, and if the warping is large, the warping of the cylindrical substrate is corrected using a press or the like.

[0009] Furthermore, Patent Document 3 assumes that a cylindrical substrate is curved and arranges multiple cylindrical targets in accordance with the curved deformation of the cylindrical substrate. Specifically, the method discloses tilting the central axis of each cylindrical target or radially offsetting it at any position along the circumference to ensure the required thickness of the bonding material between the inner circumference of the cylindrical target and the outer circumference of the cylindrical substrate.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-100930

[0013] Patent Document 2: International Publication No. 2016 / 067717

[0014] Patent Document 3: Japanese Patent Application Publication No. 2018-159105 Summary of the Invention

[0015] Problems to be solved by the invention

[0016] The invention described in Patent Document 2 addresses the following problem: if the warpage of a cylindrical substrate is measured in advance and is significant, the warpage is corrected using a press or the like. However, when the bonding material is filled, if the cylindrical substrate is preheated or if the cylindrical substrate is heated by filling the gap between the cylindrical substrate and the target with molten bonding material, there is the problem of warpage recovery after correction (also known as "warp recovery").

[0017] In addition, the invention described in patent document 3 is based on the use of a curved cylindrical substrate. Therefore, when the axial length of the cylindrical target material is less than 750 mm, the required bonding material thickness can be ensured. On the contrary, if the axial length of the cylindrical target material becomes greater than 750 mm, there is a problem of difficulty in ensuring the required bonding material thickness.

[0018] When a cylindrical sputtering target is constructed by arranging multiple cylindrical targets outside a cylindrical substrate, the gaps between the cylindrical targets can cause nodules during sputtering. Therefore, it is desirable to minimize the number of cylindrical target segments. Consequently, as the length of cylindrical sputtering targets increases over time, the axial length of the cylindrical targets also increases, leading to a trend toward longer cylindrical targets, making it impossible to limit the target length to less than 750 mm.

[0019] Therefore, the present invention relates to a sputtering target and a method for manufacturing the same that can use a warped cylindrical substrate as a constituent material, and provides a method for manufacturing a new sputtering target and a new sputtering target that can manufacture the following sputtering target, which can suppress the influence of warping of the cylindrical substrate used even if the axial length of the cylindrical target material is long and even if it is heated during filling with bonding material, that is, the cylindrical substrate is preheated when filling with bonding material, or the cylindrical substrate is heated by filling heated and molten bonding material between the cylindrical substrate and the target material. As a result, the thickness of the bonding material is uniform, the height difference between adjacent cylindrical target materials is small, and the axial distance between adjacent cylindrical target materials is uniform.

[0020] Means used to solve problems

[0021] The present invention provides a method for manufacturing a sputtering target, characterized in that it is a method for manufacturing a sputtering target comprising a cylindrical substrate and a cylindrical target material, and the method for manufacturing the sputtering target comprises the following steps:

[0022] Measure the warpage of cylindrical substrates.

[0023] The cylindrical substrate is warped in a direction opposite to the warped direction.

[0024] A plurality of cylindrical targets are arranged at intervals in the axial direction on the outer side of the processed cylindrical substrate, and the cylindrical substrate and the cylindrical targets are bonded to each other with a bonding material.

[0025] The present invention also provides a sputtering target comprising a cylindrical substrate and a cylindrical target material, wherein the cylindrical substrate and the cylindrical target material are bonded together with a bonding material.

[0026] The axial length of at least one of the above-mentioned cylindrical targets is greater than 750 mm, the difference between the maximum and minimum values ​​of the thickness of the bonding material is less than 1.0 mm, the maximum value of the height difference between the outer peripheral surfaces of adjacent cylindrical targets is less than 0.5 mm, and the difference between the maximum and minimum values ​​of the axial distance between adjacent cylindrical targets is less than 0.2 mm.

[0027] Effects of the Invention

[0028] The manufacturing method proposed by the present invention considers the warpage recovery caused by the subsequent deformation of the cylindrical substrate by heating after processing, and processes the cylindrical substrate so that it is warped by a predetermined amount in the direction opposite to the original warping. Therefore, even if the cylindrical target material has a long axial length and is heated during filling with bonding material, the effects of the warping of the cylindrical substrate can be eliminated. This allows the production of a sputtering target with a uniform bonding material thickness, minimal height differences between adjacent cylindrical targets, and a uniform axial distance between adjacent cylindrical targets.

[0029] Therefore, according to the manufacturing method proposed in the present invention, the following sputtering target can be manufactured: it is a sputtering target comprising a cylindrical substrate and a plurality of cylindrical target materials, the axial length of at least one of the above cylindrical target materials is greater than 750 mm, the difference between the maximum and minimum values ​​of the thickness of the bonding material is less than 1.0 mm, the maximum value of the height difference between the outer peripheral surfaces of adjacent cylindrical target materials is less than 0.5 mm, and the difference between the maximum and minimum values ​​of the axial distance between adjacent cylindrical target materials is less than 0.2 mm.

[0030] Furthermore, the aforementioned sputtering target, because the thickness of the bonding layer is ensured to be uniform, is not only less likely to crack during sputtering, but also has a small height difference between the outer circumferences of adjacent cylindrical targets, and the spacing of these gaps is uniform, significantly reducing the probability of abnormalities during sputtering. Furthermore, because warping (or bending) is minimal, wiggle ("ブレ" in Japanese) during target rotation is minimized, enabling the distance between the cylindrical target and the substrate to be maintained constant, resulting in uniform quality of the film formed by sputtering. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a perspective view schematically showing an example of a sputtering target.

[0032] Figure 2 This is a perspective view schematically showing an example of a warped cylindrical substrate.

[0033] Figure 3 This is a diagram schematically showing an example of a method for measuring the warpage width of a cylindrical substrate.

[0034] Figure 4 The figures are side views schematically showing an example of a method for processing a cylindrical substrate, wherein (A) shows a state before processing and (B) shows a state after processing.

[0035] Figure 5 It is a longitudinal sectional view showing an enlarged main part of an example of the manufactured sputtering target.

[0036] Figure 6This is an enlarged cross-sectional view of a main portion for explaining the height difference h and the axial distance d between adjacent targets.

[0037] Figure 7 This is a longitudinal sectional view showing a sputtering target manufacturing apparatus used in Examples. DETAILED DESCRIPTION

[0038] The present invention will be described below based on embodiments. However, the present invention is not limited to the embodiments described below.

[0039] <Main target manufacturing method>

[0040] A method for manufacturing a sputtering target according to an embodiment of the present invention (referred to as a "main target manufacturing method") is characterized in that it is a method for manufacturing a sputtering target including a cylindrical substrate 2 and a plurality of cylindrical target materials 3, 3, ..., and includes the following steps:

[0041] Measuring the warping width or warping direction of the cylindrical substrate 2 (referred to as "measuring step"),

[0042] The cylindrical substrate 2 is warped in a direction opposite to the warped direction (referred to as a "processing step"),

[0043] A plurality of cylindrical targets 3 are arranged at intervals in the axial direction on the outer side of the processed cylindrical substrate 2 , and the cylindrical substrate 2 and the cylindrical targets 3 are bonded to each other with a bonding material 4 .

[0044] (Main sputtering target)

[0045] like Figure 1 As shown, the sputtering target ("main sputtering target") 1 manufactured by the main target manufacturing method is the following sputtering target: on the outside of a cylindrical substrate 2, a plurality of cylindrical target materials 3 are arranged at intervals along the axial direction of the cylindrical substrate 2, and the cylindrical substrate 2 and the above-mentioned cylindrical target materials 3 are bonded together by a bonding material 4 (not shown).

[0046] The main sputtering target 1 will be described in detail later. Here, the components will be described first.

[0047] (Target)

[0048] The target is formed of a plurality of cylindrical targets 3 , 3 . . . . , which are arranged on the outer peripheral side of the cylindrical base material 2 at appropriate intervals in the axial direction of the cylindrical base material 2 .

[0049] Each cylindrical target material 3 only needs to have an inner diameter larger than the outer diameter of the cylindrical base material 2 .

[0050] Some have pointed out the following problem: the length of cylindrical targets tends to increase year by year. Furthermore, if the length of a cylindrical target increases, particularly if it exceeds 750 mm, it becomes difficult to ensure the thickness of the bonding material. However, the main target manufacturing method can eliminate this problem and further enhance the effects of the present invention.

[0051] Therefore, from the perspective of better exerting the effect of the present invention, the axial length L3 of at least one of the above-mentioned multiple cylindrical targets 3, 3... is preferably greater than 750 mm, more preferably greater than 850 mm, further preferably greater than 950 mm, and further preferably greater than 1400 mm.

[0052] The material of the cylindrical target 3 is not particularly limited. For example, oxides containing one or more of Cu, Al, In, Sn, Ti, Ba, Ca, Zn, Mg, Ge, Y, La, Al, Si, Ga, and W can be cited.

[0053] Examples of the oxide include: In-Sn-O, In-Ti-O, In-Ga-Zn-O, In-Zn-Sn-O, In-Ga-Zn-Sn-O, Ga-Zn-O, In-Zn-O, In-Ga-O, IWO, I-Zn-WO, Z n-O, Sn-Ba-O, Sn-Zn-O, Sn-Ti-O, Sn-Ca-O, Sn-Mg-O, Zn-Mg-O, Zn-Ge-O, Zn-Ca-O, Zn-Sn-Ge-O, Cu2O, CuAlO2, CuGaO2, CuInO2, etc.

[0054] (Cylindrical substrate)

[0055] The cylindrical substrate 2 is ideally formed into a cylindrical shape with a straight central axis and an outer peripheral surface parallel to the axis. Figure 2 As shown, the newly used cylindrical substrate 2 or the recycled cylindrical substrate 2 is warped in a curved shape, in other words, in an arched shape, and the outer peripheral surface of the cylindrical substrate 2 has a deviation from the linear axis direction.

[0056] The material of the cylindrical base material 2 may be any metal such as Ti, SUS, or Cu, but is not limited thereto.

[0057] (Joint material)

[0058] The bonding material 4 is a material that is supplied in a molten state to the gap between the cylindrical substrate 2 and each cylindrical target material 3 arranged at a specified position on its outer circumference when manufacturing the sputtering target, and solidifies after filling the gap to bond the cylindrical substrate 2 and the cylindrical target material 3.

[0059] The material of the bonding material 4 is not particularly limited as long as it can be used for bonding the target and the substrate. Examples thereof include low melting point solders such as In metal, In-Sn metal, or In alloy metals containing In with trace amounts of metal components added thereto.

[0060] Since the low melting point solder has a melting point of 150 to 250° C., when filling the bonding material 4 , the bonding material 4 is usually heated to 150 to 300° C. to be melted.

[0061] <Measurement process>

[0062] In the measuring step, the warping width or warping direction of the cylindrical base material 2 serving as the constituent material is measured.

[0063] The method for measuring the warpage amplitude is not particularly limited. For example, the cylindrical substrate 2 can be rotated along its axis to measure the displacement amplitude of the outer circumference, i.e., the warpage amplitude. Alternatively, the cylindrical substrate 2 can be placed horizontally on a platform and the distance between the smooth surface of the platform and the outer circumference 2a of the cylindrical substrate 2 can be measured along a perpendicular line erected on the platform. Other methods are also possible.

[0064] The position for measuring the warpage width may be one position or two or more positions in the longitudinal direction of the cylindrical substrate 2 .

[0065] The cylindrical substrate 2 is often warped in an arched shape. Therefore, if the warping width is measured near the center in the longitudinal direction, the maximum warping width and the warping direction can be measured.

[0066] However, warping is not necessarily limited to an arched shape, so it is preferable to measure the warping amplitude at multiple locations spaced apart along the length. For example, measurement is preferably performed at intervals of 100 mm to 1000 mm, more preferably at intervals of 200 mm or more and 800 mm or less, and particularly preferably at intervals of 500 mm or less.

[0067] An example of a specific method for measuring the warpage width will be described.

[0068] like Figure 3 As shown, the cylindrical substrate 2 is set horizontally and rotatable, and the dial gauge 5 is placed against the outer peripheral surface 2a of the cylindrical substrate 2. The cylindrical substrate 2 is rotated one circle, and the reading of the dial gauge 5 is measured. Then, the maximum value H of the reading of the dial gauge 5 can be max With the minimum value H min The difference (H max -H min ) as the warping amplitude.

[0069] At this time, any means of rotating the cylindrical substrate 2-axis may be used, such as placing it between two rotating rollers and rotating it, or placing the cylindrical substrate near both ends in the grooves of a support having V-shaped grooves and rotating it by hand or with rollers.

[0070] In the measurement step, the original warping width X or warping direction of the obtained cylindrical substrate 2 may be measured as described above, or the obtained cylindrical substrate 2 may be heated and then the warping width Y or warping direction of the heated cylindrical substrate 2 may be measured as described above.

[0071] When heating the cylindrical substrate 2 and measuring the warpage amplitude Y or warpage direction of the heated cylindrical substrate, the heating temperature of the cylindrical substrate 2 is preferably estimated to be the temperature at which the cylindrical substrate 2 is heated when the bonding material is filled, that is, when the heated and molten bonding material 4 is filled between the cylindrical substrate 2 and the cylindrical target 3, or the temperature at which the cylindrical substrate 2 is heated by the filled bonding material 4. However, if the temperature is too high, there is a possibility that the surface of the cylindrical substrate 2 will oxidize. From this point of view, the heating temperature of the cylindrical substrate 2 at this time is preferably heated to a surface temperature of 150 to 300°C, more preferably to 160°C or higher and 240°C or lower, and even more preferably to 170°C or higher and 230°C or lower.

[0072] There is no particular limitation on the method for heating the cylindrical substrate 2. For example, the substrate may be placed in an electric furnace and heated from the outside, or a heater may be provided inside the substrate and heated from the inside.

[0073] <Processing process>

[0074] In the processing step, the cylindrical base material 2 is processed so as to be warped by a predetermined width α in the direction opposite to the originally warped direction.

[0075] For example, Figure 4 As shown, at the measuring position in the measuring process, pressure is applied in the direction opposite to the warping direction measured in the above-mentioned measuring process to bend the cylindrical substrate 2, as shown in FIG. Figure 4 As shown in (B), the cylindrical base material 2 may be processed so as to be warped by a width α in the opposite direction to the warped direction, in other words, so as to be displaced by a distance α from the linear axis.

[0076] Regarding the location of pressure application, for example, if the cylindrical substrate 2 is warped into an arched shape, pressure can be applied to a point in the axial center to cause deformation. Furthermore, pressure is preferably applied to the location measured during the measurement step. For example, measurements are performed at intervals of 100 mm to 1000 mm, and pressure is preferably applied to cause deformation at each measurement point.

[0077] The warping width α (mm) of the cylindrical substrate 2 in the direction opposite to the warped direction is preferably determined based on the warping width X or Y measured in the above-mentioned measurement step. This is because the larger the warping width X or Y, the greater the extent of the warping recovery caused by heating after processing.

[0078] For example, in the measurement process, when the original warping amplitude of the obtained cylindrical substrate 2 is measured to obtain the warping amplitude X, the warping amplitude α (mm) is preferably set to X (mm) × (0.10~2.00), among which it is more preferably set to X (mm) × 0.50 or more or X (mm) × 1.50 or less, among which it is further preferably set to X (mm) × 0.80 or more or X (mm) × 1.40 or less, among which it is further preferably set to X (mm) × 0.90 or more or X (mm) × 1.30 or less.

[0079] In addition, in the measurement process, when the obtained cylindrical substrate 2 is heated and the warping amplitude of the heated cylindrical substrate 2 is measured to obtain the warping amplitude, the warping amplitude α (mm) is preferably set to Y (mm) × (0.50~1.50), among which it is more preferably set to Y (mm) × 0.80 or more or Y (mm) × 1.40 or less, among which it is further preferably set to Y (mm) × 0.90 or more or Y (mm) × 1.30 or less, among which it is further preferably Y (mm) × 0.95 or more or Y (mm) × 1.25 or less.

[0080] If heating is actually performed and the warpage width Y after heating is measured, and the warpage width α is determined based on the warpage width Y, the width α can be determined in consideration of the obtained heating behavior of the cylindrical substrate 2 , thereby further reducing warpage recovery.

[0081] As a processing method for applying pressure to the cylindrical substrate 2 to cause it to warp, for example, the following can be cited. Figure 4 As shown in (A), a method of applying pressure to the cylindrical substrate 2 in the direction opposite to the warping direction at the measurement position (one or more locations) in the measurement process. Figure 4 P in (A) represents a pressing direction. In this case, as a means of applying pressure, for example, mechanical pressing, forging, etc. can be cited.

[0082] However, any means may be adopted as long as it is a means that can cause the cylindrical base material 2 to warp by a desired amount.

[0083] At this time, in order to prevent the circularity of the cylindrical base material from changing, an arc-shaped terminal or the like that matches the shape of the cylindrical base material 2 may be used as the terminal for applying pressure.

[0084] Furthermore, heat treatment (annealing) may be further performed as needed.

[0085] Alternatively, the cylindrical substrate 2 may be repeatedly warped by applying pressure. Specifically, the cylindrical substrate 2 may be repeatedly warped by applying pressure, further warping, and so on, until the cylindrical substrate 2 is finally warped by a predetermined width α.

[0086] Alternatively, the cylindrical substrate 2 may be repeatedly subjected to a process of heating and pressurizing the cylindrical substrate 2 (measuring the warpage width Y), further heating and pressurizing the cylindrical substrate 2, and so on, to warp the cylindrical substrate 2 until the cylindrical substrate 2 is finally warped by a predetermined width α. In this case, the warpage width Y may be measured first after heating.

[0087] <Cylindrical target placement>

[0088] Using the cylindrical substrate 2 processed as described above, a plurality of cylindrical targets 3 are arranged on the outer peripheral side of the cylindrical substrate 2 at appropriate intervals in the axial direction.

[0089] The cylindrical targets 3 are preferably arranged in a row at intervals of 0.15 mm to 0.50 mm in the axial direction.

[0090] <Joining>

[0091] After the cylindrical target material 3 is configured as described above, the cylindrical substrate 2 and the cylindrical target material 3 are heated, the gap between the cylindrical substrate 2 and the cylindrical target material 3 is filled with molten bonding material 4, the bonding material 4 is cooled, and each cylindrical target material 3 is bonded to the periphery of the cylindrical substrate 2 through the bonding material 4.

[0092] Before filling the bonding material 4 , the temperature at which the cylindrical base material 2 and the cylindrical target 3 are heated is preferably set to be equal to or higher than the temperature of the bonding material 4 .

[0093] The temperature of the bonding material 4 when filling the bonding material 4 is a temperature higher than the melting point of the bonding material, preferably heated to 150-300°C, more preferably heated to 160°C or higher or 240°C or lower, and further preferably heated to 170°C or higher or 230°C or lower.

[0094] As the method of filling and cooling the bonding material, a known method can be adopted.

[0095] Main sputtering target

[0096] According to the main target manufacturing method, the influence of the warping of the cylindrical substrate 2 can be eliminated even when heated during filling of the bonding material, and thus the following main sputtering target can be manufactured.

[0097] As a preferred example of a main sputtering target, a sputtering target having a cylindrical substrate 2 and multiple cylindrical target materials 3, 3... can be listed, wherein the axial length L3 of at least one of the above multiple cylindrical target materials 3, 3... is greater than 750 mm, the difference between the maximum and minimum values ​​of the thickness of the bonding material 4 is less than 1.0 mm, the maximum value of the height difference h between the outer peripheral surfaces 3a, 3a of adjacent cylindrical target materials 3, 3 is less than 0.5 mm, and the difference between the maximum and minimum values ​​of the axial distance d between adjacent cylindrical target materials 3, 3 is less than 0.2 mm.

[0098] Furthermore, from the viewpoint of further exerting the effects of the present invention, the length of the cylindrical substrate 2 is preferably 2.0 m to 4 m, more preferably 3.0 m or more and 3.8 m or less, and even more preferably 3.3 m or more and 3.7 m or less.

[0099] The outer diameter of the cylindrical substrate 2 is preferably 125 mm to 140 mm, more preferably 130 mm or more and 135 mm or less, and even more preferably 132 mm or more and 134 mm or less.

[0100] The inner diameter of the cylindrical target 3 is preferably 127 mm to 142 mm, more preferably 132 mm or more and 137 mm or less, and even more preferably 134 mm or more and 136 mm or less.

[0101] The wall thickness of the cylindrical target 3 is preferably 5 mm to 20 mm, more preferably 6 mm or more and 16 mm or less, and even more preferably 8 mm or more and 13 mm or less.

[0102] From the viewpoint of further exerting the effects of the present invention, the axial length L3 of at least one of the cylindrical targets 3 is preferably 750 mm to 1500 mm, more preferably 850 mm or more or 1450 mm or less, and even more preferably 950 mm or more or 1450 mm or less.

[0103] If the difference between the maximum and minimum thicknesses of the bonding material 4 is less than 1.0 mm, the thickness of the bonding material 4 is ensured to be uniform, thereby preventing, for example, insufficient cooling in thin portions of the bonding material that may cause target breakage, and suppressing the generation of cracks during sputtering.

[0104] From this viewpoint, the difference between the maximum value and the minimum value of the thickness of the bonding material 4 is more preferably 0.5 mm or less, and further preferably 0.3 mm or less.

[0105] In this case, the thickness of the bonding material 4 is preferably 0.5 mm or more, more preferably 0.7 mm or more, and even more preferably 1 mm or more.

[0106] The thickness of the bonding material 4 can be measured using an ultrasonic flaw detector.

[0107] If the maximum value of the height difference h between the outer peripheral surfaces 3a, 3a of adjacent cylindrical targets 3, 3, that is, the maximum value of the height difference h between the adjacent outer edges in the axial direction of the outer peripheral surfaces 3a, 3a of a pair of cylindrical targets 3, 3 adjacent in the axial direction, is 0.5 mm or less, the probability of abnormalities occurring during sputtering, specifically the generation of arcs and the accompanying generation of debris and cracks, can be reduced. On the other hand, if the maximum value of the height difference h exceeds 0.5 mm, one side of the cylindrical target 3 will protrude, potentially causing adverse effects such as abnormal discharge at the protruding edge.

[0108] From this viewpoint, the maximum value of the height difference h is more preferably 0.3 mm or less, and further preferably 0.2 mm or less.

[0109] Note that the height difference h can be measured using, for example, a depth gauge or the like.

[0110] Furthermore, if the difference between the maximum and minimum values ​​of the axial distance (spacing) d between adjacent cylindrical targets 3 is 0.2 mm or less, the probability of abnormalities during sputtering, such as contact between the ends due to thermal expansion during sputtering, causing chipping and cracking, can be further reduced. For example, in areas where the axial distance d is large, the cylindrical substrate 2 is exposed, and substrate components may be splashed and mixed into the film as impurities. On the other hand, in areas where the axial distance d is small, adjacent cylindrical targets 3 may collide with each other due to thermal expansion caused by sputtering, potentially causing the cylindrical targets 3 to crack.

[0111] From this viewpoint, the difference between the maximum value and the minimum value of the axial distance d between adjacent cylindrical targets 3 , 3 is more preferably 0.15 mm or less, and further preferably 0.1 mm or less.

[0112] The axial distance (interval) d can be measured using, for example, a feeler gauge.

[0113] <Description of statement>

[0114] In this specification, when expressed as "A to B" (where A and B are arbitrary numbers), unless otherwise specified, it also includes the meaning of "A or more and B or less", and the meaning of "preferably greater than A" or "preferably less than B".

[0115] In addition, when expressed as "A or more" (A is an arbitrary number) or "B or less" (B is an arbitrary number), it also includes the meaning of "preferably greater than A" or "preferably less than B".

[0116] Example

[0117] The present invention will be further described with reference to the following examples, which are not intended to limit the present invention.

[0118] <Example 1>

[0119] A cylindrical substrate (length 3400 mm, diameter 133 mm, wall thickness 4 mm) as a recycled product is placed on a pedestal that can be supported in an axially rotatable manner. The pedestal is set horizontally and can be axially rotatable. A dial gauge is fixed from above against the outer surface of the longitudinal center of the cylindrical substrate. The cylindrical substrate is rotated once and the reading of the dial gauge is measured. The maximum value H is the value of the reading. max With the minimum value H min The difference (H max -H min ) was measured as the warpage width X (initial).

[0120] Next, the cylindrical substrate was placed in an electric furnace and heated so that the surface temperature was maintained at 230° C. for 1 hour. The same operation as above was repeated to measure the warpage width Y (after heating) after heating.

[0121] Next, a press machine was used to pressurize the longitudinal center of the cylindrical substrate in the direction (-direction) opposite to the warped direction (+direction) and process the cylindrical substrate so as to warp it in the opposite direction (-direction) by a width α (=Y×1.0).

[0122] Next, using the cylindrical substrate processed as described above, Figure 7 The manufacturing apparatus 40 shown manufactures an ITO cylindrical sputtering target as follows.

[0123] That is, four ITO cylindrical split targets with an outer diameter of 153 mm, an inner diameter of 133 mm, and lengths of 300 mm, 750 mm, 750 mm, and 300 mm were prepared, the outer peripheral surface of the cylindrical split target was covered with a heat-resistant film and tape, and In solder was primed on the joint surface (inner peripheral surface) using an ultrasonic welding iron.

[0124] On the other hand, an ultrasonic soldering iron was also used to apply an indium solder primer to the bonding surface (outer peripheral surface) of the cylindrical substrate processed as described above.

[0125] The cylindrical substrate is mounted on the substrate holding portion 43 c equipped with an O-ring 48 made of Teflon (registered trademark).

[0126] Next, a Teflon (registered trademark) O-ring 47 was attached to the target holder 43b, and one of the cylindrical split targets was mounted on the target holder 43b. At this point, the offset between the lower end of the cylindrical substrate and the lower end of the cylindrical split target was adjusted to 0.1 mm using the lower holding member 43. Furthermore, a gap 49 was formed between the cylindrical substrate and the cylindrical split target.

[0127] Furthermore, the remaining cylindrical split targets are piled up on the above-mentioned cylindrical split targets. An O-ring 51 made of Teflon (registered trademark) with a thickness of 0.5 mm is sandwiched between the cylindrical split targets. An O-ring 50 is installed on the cylindrical split target placed at the top, and the top cylindrical split target is installed on the target holding portion 44 b, and the cylindrical target is pressed from the top side by the target holding portion 44 b. At this time, the positions of the 9 cylindrical split targets are adjusted, and all height differences between the cylindrical split targets are set to be less than 0.2 mm. In this way, the upper end of the cylindrical target is maintained by the target holding component 44.

[0128] Next, the substrate pressing portion 45b was pressed against the upper end of the cylindrical substrate, and the upper end of the cylindrical substrate was held by the substrate holding member 45. At this time, the position of the jig was adjusted while measuring the distance between the surface of the cylindrical target and the surface of the cylindrical substrate with a depth gauge so that the offset between the upper end of the cylindrical substrate and the upper end of the cylindrical target was 0.1 mm or less.

[0129] Finally, the lower holding component 43 is fixed to the titanium connecting component 46 using the fixing part 43d, the target material holding component 44 is fixed to the titanium connecting component 46 using the fixing part 44c, and the substrate holding component 45 is fixed to the titanium connecting component 46 using the fixing part 45c, thereby firmly fixing the cylindrical substrate and the cylindrical target material to the manufacturing device 40.

[0130] The production apparatus 40 , the cylindrical substrate, and the cylindrical target were heated to 180°C.

[0131] An amount of melted In solder at 175° C. sufficient for joining the cylindrical target and the cylindrical base material is injected into the cavity 49 from the upper side of the target holding member 44 .

[0132] The melted solder injected into the manufacturing device 40 , the cylindrical substrate, the cylindrical target, and the cavity 49 was cooled.

[0133] After confirming that the In solder was solidified, the produced ITO cylindrical sputtering target (sample) was removed from the manufacturing apparatus 40 , the O-ring was removed, and the In solder remaining between the cylindrical split target materials was scraped off.

[0134] The thickness of the bonding material of the ITO cylindrical sputtering target (sample) prepared as described above was measured using an ultrasonic flaw detector (FS LINE, manufactured by Hitachi Power Solutions Co., Ltd.) as follows. Specifically, the thickness of the bonding layer was calculated from the difference in detection time between the reflected wave at the interface between the target and the bonding layer and the reflected wave at the interface between the bonding layer and the substrate, and the propagation velocity of the ultrasonic wave in the bonding layer. A 10 MHz probe was used, and the ultrasonic wave propagation velocity in the bonding layer (In metal) was set to 2700 m / s.

[0135] The thickness of the bonding material was measured at two points 10 mm inward from each end of the target segment in the axial direction, and at points equally divided so that the distance between these two points would be 50 mm or less. Furthermore, the thickness of the bonding material was measured at twelve points (0°, 30°, 60°, ..., and 330°) at 30° intervals along the circumference of each of these axial measurement points. Measurements were taken at these locations for each target segment after bonding within a single substrate, and the difference between the maximum and minimum values ​​was taken as the bonding material thickness difference.

[0136] Furthermore, all height differences h between adjacent targets were measured using a depth gauge, and the maximum value of the height differences h was determined.

[0137] In addition, all axial distances d between adjacent targets were measured using a feeler gauge, and the difference between the maximum and minimum values ​​was calculated.

[0138] All height differences h and axial distances d between adjacent targets were measured at 12 locations (positions at 0°, 30°, 60°, ..., and 330°) at intervals of 30° along the circumferential direction.

[0139] <Example 2>

[0140] An ITO cylindrical sputtering target (sample) was produced in the same manner as in Example 1 except that the longest cylindrical target was changed to 850 mm, and various values ​​were measured.

[0141] <Example 3>

[0142] An ITO cylindrical sputtering target (sample) was produced in the same manner as in Example 1 except that the longest cylindrical target was changed to 1100 mm, and various values ​​were measured.

[0143] <Example 4>

[0144] An ITO cylindrical sputtering target (sample) was produced in the same manner as in Example 1 except that the longest cylindrical target was changed to 1450 mm, and various values ​​were measured.

[0145] <Example 5>

[0146] In Example 4, heating of the cylindrical substrate was omitted. Specifically, instead of heating the cylindrical substrate in an electric furnace and then measuring the warping amplitude Y after heating, an ITO cylindrical sputtering target (sample) was produced and various values ​​were measured in the same manner as in Example 4, except that the cylindrical substrate was pressed in the direction (-direction) opposite to the warped direction (+direction) using a press machine at the longitudinal center of the cylindrical substrate, thereby warping the cylindrical substrate in the opposite direction (-direction) by a width α (=X×1.0).

[0147] <Example 6>

[0148] In Example 3, except that the material of the cylindrical target was changed to IGZO, an IGZO cylindrical sputtering target (sample) was produced in the same manner as in Example 3, and various values ​​were measured.

[0149] Comparative Example 1

[0150] An ITO cylindrical sputtering target (sample) was produced in the same manner as in Example 2, except that the processing for warping the cylindrical substrate was not performed, and various values ​​were measured.

[0151] Comparative Example 2

[0152] An ITO cylindrical sputtering target (sample) was manufactured in the same manner as in Example 2, except that the cylindrical substrate was not warped to the opposite side of the original warping direction in the processing step of warping the cylindrical substrate, and various values ​​were measured.

[0153] Table 1

[0154]

[0155] The warping amplitude of the cylindrical substrate used is measured, and the cylindrical substrate is pressurized in a direction opposite to the original warping direction so as to be processed in a manner that warps in the opposite direction to the warping direction. Therefore, even if the axial length of the cylindrical target is long, that is, even if the axial length of at least one cylindrical target is more than 750 mm, and even if it is heated during the filling of the bonding material, that is, the cylindrical substrate is preheated when the bonding material is filled, or the heated and molten bonding material is filled between the cylindrical substrate and the target to heat the cylindrical substrate, the influence of the warping of the cylindrical substrate can be eliminated. As a result, it can be seen that: the difference between the maximum and minimum values ​​of the thickness of the bonding material can be reduced, the height difference between the outer peripheral surfaces of adjacent cylindrical targets can be reduced, and the difference between the maximum and minimum values ​​of the axial distance between adjacent cylindrical targets can be reduced.

[0156] Explanation of symbols

[0157] 1Sputtering target

[0158] 2. Base material

[0159] 2a outer surface

[0160] 3 Target

[0161] 4. Bonding materials

[0162] 5 micrometer

[0163] 40 Manufacturing Equipment

[0164] 43 lower retaining member

[0165] 43b target holding portion

[0166] 43c substrate holding portion

[0167] 43d fixings

[0168] 44 target holding component

[0169] 44b target holding portion

[0170] 44c fixings

[0171] 45 substrate holding component

[0172] 45b substrate pressing portion

[0173] 45c fixings

[0174] 46 connecting parts

[0175] 47O ring

[0176] 48O ring

[0177] 49 gap

[0178] 50O ring

[0179] 51O ring

Claims

1. A method for manufacturing a sputtering target, characterized in that: The present invention relates to a method for producing a sputtering target comprising a cylindrical substrate and a cylindrical target material, and the method comprises the following steps: The process of measuring the warpage of a cylindrical substrate, The step of performing a process for warping the cylindrical base material in the direction opposite to the warped direction so as to achieve a state in which the cylindrical base material is warped from the linear axis. A plurality of cylindrical targets are arranged at intervals in the axial direction on the outer side of the processed cylindrical substrate, and the cylindrical substrate and the cylindrical targets are bonded with a bonding material. In the measuring step, after heating the cylindrical substrate, the warpage width Y of the heated cylindrical substrate is measured. In the processing step, when the warping width Y is measured in the measuring step, the cylindrical substrate is warped in the opposite direction to the warped direction by only a width of Y×(0.50 to 1.50) so that the cylindrical substrate is warped from the linear axis.

2. The method for manufacturing a sputtering target according to claim 1, wherein: In the processing step, when the original warping amplitude X of the cylindrical substrate is measured in the measuring step, the cylindrical substrate is processed to be warped in the opposite direction of the warping direction by only an amplitude of X×(0.10 to 2.00) to achieve a state in which the cylindrical substrate is warped from the linear axis.

3. The method for manufacturing a sputtering target according to claim 1, wherein: In the measuring step, the cylindrical substrate is heated to 150 to 300° C., and then the warpage width Y of the heated cylindrical substrate is measured.

4. The method for producing a sputtering target according to claim 1 or 2, wherein: In the measuring step, the width of displacement of the outer peripheral surface of the cylindrical substrate is measured as the warpage width.

5. The method for producing a sputtering target according to claim 1 or 2, wherein: At least one of the cylindrical targets has an axial length of 750 mm or more.

6. The method for producing a sputtering target according to claim 1 or 2, wherein: The difference between the maximum and minimum thicknesses of the bonding material of the prepared sputtering target is less than 1.0 mm, the maximum height difference between the outer peripheral surfaces of adjacent cylindrical target materials is less than 0.5 mm, and the difference between the maximum and minimum axial distances between adjacent cylindrical target materials is less than 0.2 mm.

7. A sputtering target comprising a cylindrical substrate and a cylindrical target material, wherein the cylindrical substrate and the cylindrical target material are bonded together using a bonding material. The axial length of at least one of the cylindrical targets is 750 mm to 1500 mm, the difference between the maximum and minimum thicknesses of the bonding material is 0.5 mm or less, the maximum height difference between the outer circumferential surfaces of adjacent cylindrical targets is 0.5 mm or less, and the difference between the maximum and minimum axial distances between adjacent cylindrical targets is 0.2 mm or less. The length of the cylindrical substrate is greater than or equal to 3.0 m.

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